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POIOKit device adding/removal notifications - only fire once?
 

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  1. POIOKit device adding/removal notifications - only fire once?
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    <p>I have been trying to get notified when a specific USB device is added or removed. I have read 'Accessing Hardware From Applications' document and have a bare-bones demo application, mainly based on the code provided in that document.</p> <p>It works the first time a device is added or removed, but after that my callbacks never get called. I cannot work out why? Can anyone spot where I am going wrong?</p> <p>(xcode project if you would like to test) <a href="http://monkeyfood.com/testIOKitNOtificaiton.zip" rel="nofollow">http://monkeyfood.com/testIOKitNOtificaiton.zip</a></p> <p>Thanks.</p> <pre><code>// // AppDelegate.m // testIOKitNotification // // Created by Diggory Laycock on 23/07/2012. // Copyright (c) 2012 MonkeyFood.com. All rights reserved. // #import "AppDelegate.h" @implementation AppDelegate // Arduino USB info #define matchVendorID 0x2341 #define matchProductID 0x0043 #pragma mark - #pragma mark C Callback functions #pragma mark - void usbDeviceAppeared(void *refCon, io_iterator_t iterator){ NSLog(@"Matching USB device appeared"); } void usbDeviceDisappeared(void *refCon, io_iterator_t iterator){ NSLog(@"Matching USB device disappeared"); } @synthesize window = _window; #pragma mark - #pragma mark Application Methods #pragma mark - - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { io_iterator_t newDevicesIterator; io_iterator_t lostDevicesIterator; newDevicesIterator = 0; lostDevicesIterator = 0; NSLog(@" "); NSMutableDictionary *matchingDict = (__bridge NSMutableDictionary *)IOServiceMatching(kIOUSBDeviceClassName); if (matchingDict == nil){ NSLog(@"Could not create matching dictionary"); return; } [matchingDict setObject:[NSNumber numberWithShort:matchVendorID] forKey:(NSString *)CFSTR(kUSBVendorID)]; [matchingDict setObject:[NSNumber numberWithShort:matchProductID] forKey:(NSString *)CFSTR(kUSBProductID)]; // Add notification ports to runloop IONotificationPortRef notificationPort = IONotificationPortCreate(kIOMasterPortDefault); CFRunLoopSourceRef notificationRunLoopSource = IONotificationPortGetRunLoopSource(notificationPort); CFRunLoopAddSource([[NSRunLoop currentRunLoop] getCFRunLoop], notificationRunLoopSource, kCFRunLoopDefaultMode); kern_return_t err; err = IOServiceAddMatchingNotification(notificationPort, kIOMatchedNotification, (__bridge CFDictionaryRef)matchingDict, usbDeviceAppeared, (__bridge void *)self, &amp;newDevicesIterator); if (err) { NSLog(@"error adding publish notification"); } [self matchingDevicesAdded: newDevicesIterator]; NSMutableDictionary *matchingDictRemoved = (__bridge NSMutableDictionary *)IOServiceMatching(kIOUSBDeviceClassName); if (matchingDictRemoved == nil){ NSLog(@"Could not create matching dictionary"); return; } [matchingDictRemoved setObject:[NSNumber numberWithShort:matchVendorID] forKey:(NSString *)CFSTR(kUSBVendorID)]; [matchingDictRemoved setObject:[NSNumber numberWithShort:matchProductID] forKey:(NSString *)CFSTR(kUSBProductID)]; err = IOServiceAddMatchingNotification(notificationPort, kIOTerminatedNotification, (__bridge CFDictionaryRef)matchingDictRemoved, usbDeviceDisappeared, (__bridge void *)self, &amp;lostDevicesIterator); if (err) { NSLog(@"error adding removed notification"); } [self matchingDevicesRemoved: lostDevicesIterator]; // CFRunLoopRun(); // [[NSRunLoop currentRunLoop] run]; } #pragma mark - #pragma mark ObjC Callback functions #pragma mark - - (void)matchingDevicesAdded:(io_iterator_t)devices { io_object_t thisObject; while ( (thisObject = IOIteratorNext(devices))) { NSLog(@"new Matching device added "); IOObjectRelease(thisObject); } } - (void)matchingDevicesRemoved:(io_iterator_t)devices { io_object_t thisObject; while ( (thisObject = IOIteratorNext(devices))) { NSLog(@"A matching device was removed "); IOObjectRelease(thisObject); } } @end </code></pre>
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